The invention relates to an apparatus for the application of hot melt glue onto the back surfaces of blocks, preferably of book blocks during block transport within a block conveyor with block conveying means carrying the blocks in their longitudinal direction with the block back surfaces oriented downward, and with glueing rollers arranged below said means of block transport. By the object of DD Letters Pat. No. 119 555, an apparatus for the glueing of block back surfaces, preferably of book blocks, has become known, wherein one or a plurality of the glueing rollers are arranged obliquely to the block back surfaces when viewing these back surfaces in the direction of transport, and perpendicularly or at an angle to the direction of transport, so that the block back surfaces will be spread out fanlike thereby. Herein, the lateral fanning out of block back surfaces during the glueing sequence is accomplished by one or a plurality of guide rails or guide rollers extending into the zone within which the block back surfaces are being transported. In this apparatus, the glueing rollers may furthermore be designed in the shape of a cone or the frustum of a cone.
The apparatus as above is, however, suitable only for the dispersion glueing of blocks. Since the glueing rollers are arranged at an angle to the glue pans and are also pivotable, the glue pans are of a relatively low height so that the glueing rollers will have only low immersion at least over a part of the arrangement. Furthermore, not every glueing roller is provided with its separate glue pan. Despite the advantageous principle of the solution as per invention of DD Letters Pat. No. 119 555, it is a consequence of the aforenoted criteria that this apparatus is particularly unsuitable for application with hot melt processes. Due to the need for a low design height and due to the functioning of the apparatus not allowing separation of individual glue pans, thermal losses due to inadequate heating of the hot melt glue would be of such magnitude that during the application onto the block back surfaces the glue would not be at a temperature that would result in a tearing resistance of the page edges higher than attainable in the dispersion glueing process. Glueing of the blocks is furthermore also interferred with, since there may be very different glue levels within individual glue pans, and gaging of these levels is not ensured herein. Finally, optional arrangement of one or a plurality of glueing rollers will not in every instance allow attaining the intended effect of this apparatus as attained with an arrangement of glueing rollers described in the embodiment of DD Letters Pat. No. 119 555.